The trigger and DAQ system of the surface detector array of the telescope array experiment

The surface detector (SD) array of the Telescope Array (TA) experiment consists of 507 plastic scintillation detectors, deployed on a square grid with 1.2 km spacing. The trigger and DAQ system of the TA surface detector array is the key to provide reliable SD data. To achieve efficient SD DAQ, we divided the whole area into three regions which have one communication tower with one host electronics system respectively. The host communicates via radios with each surface detector in the region. We developed a real-time system that monitors a variety of information in the background for SD calibration and maintenance. The trigger and DAQ system began full operation in March, 2008. We installed a cross-boundary trigger between neighboring regions to make the shower trigger efficiency uniform in the whole region except the border of the array in November, 2008. Here we report the detail of the TA SD trigger and DAQ system.